Pharamalat Everfresh milk tastes sour

I purchased milk at Spar from the Pharmalat range and logged a complaint with them when I noticed that the milk tastes off. I had opened 3x 1litre bottles by then. They followed through right up to collection for testing. My problem now is I’m sitting with 9litres of milk that I’m not sure what I must do as they’re ignoring all efforts to get feedback from the testing. Pharamalt must tell me the outcome from the test and what I should do with the 9litres of milk occupying my cupboard